1. Technical Field
The present invention relates to the field of validating data and, more particularly to the detection of errors in software operational commands and data retrieval from random access memory.
2. Description of the Prior Art
Software, upon retrieval from program memory where it is stored, is run by a central processing unit. Occasionally, the retrieval processor other factors can create errors in the commands and data retrieved so that the software, when run, can enter an endless loop or can get lost outside of its normal flow and execute garbage results. Obviously, in these instances, the software becomes no longer predictable when it is run and can not be perfectly designed to anticipate these errors, correct itself or to raise an alarm.
In such cases, it is believed known in the art to implement a timer either directly associated with the central processing unit or indirectly at a peripheral unit where some form of expected action is to take place within a predetermined period of time. Such timers then are called upon to be initiated by the central processing unit, wait until the predetermined period of time expires and then initiate an alarm. Thereafter, the software, for example, can be recalled from memory, and the process the software is responsible for controlling, can be reinitiated.
Such a known technique has been appropriately named a "watch dog timer". The problem with such a technique is that the process is inherently slow and fails to react to potential errors as they occur. Consequently, there is a need, especially in real time environments, such as in the art of designing program controlled telecommunications transmission and switching equipment, for a more responsive arrangement where software errors can be detected more quickly and efficiently.